1. Field
The described technology relates generally to an organic light emitting diode display, and more particularly, to an organic light emitting diode display with a differential capping layer.
2. Description of the Related Art
An organic light emitting diode (OLED) display is a self emissive display device that displays images with organic light emitting diodes. The organic light emitting diode display differs from a liquid crystal display (LCD) in that it does not require a separate light source, and has relatively small thickness and weight. Furthermore, as the organic light emitting diode display involves high quality characteristics such as low power consumption, high luminance, and short response time, it is spotlighted as a next generation display device for portable electronic appliances.
The organic light emitting diode usually includes an anode, a cathode, and an organic emissive layer disposed between the anode and the cathode. With the organic light emitting diode, holes from the anode and electrons from the cathode are combined within the organic emissive layer so as to form excitons being electron-hole pairs, and when the excitons return to the ground state, energy is generated to thereby emit light.
The anode and the cathode of the organic light emitting diode are formed with one of a reflective electrode and a semitransparent electrode, respectively. The organic light emitting diode has such an optical characteristic such that the maximum constructive interference occurs at a specific thickness per respective wavelengths of the emitted light.
However, all the organic light emitting diodes have the same thickness per respective color pixels, while the reflective electrode and the semitransparent electrode are differentiated in optical constructive interference from each other. Accordingly, it cannot be expected to achieve desired color reproducibility and optical efficiency with respect to all the colors.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.